accident in the snow. i don't drive in the snow anymore. i am a terrified passenger if it's snowing. i become paralyzed. i cry. i know it's irrational. what's going on with my brain, cara? do you know? >> yeah, or it sounds like it could be a post-traumatic stress disorder. >> larry: what is post-traumatic stress. something happens to you and -- >> and you experience hypervigilance, heightened levels of stress and you actually have behaviors in your life that are so difficult that they, you know, they make your life difficult to navigate after that. we see it obviously in war time. we see it after trauma, after abuse, after rape, and after things like car accidents. >> larry: we didn't hear it, though, until vietnam. never heard it after world war ii. >> it was shell shock. different sayings. >> one thing about this case, ptsd can create all of those symptoms. as well as triggering panic attacks and you have one trial learning when you are in a situation that's highly negative.